Synthesis and Photoisomerization of Diarylcyclobutenes

Abstract

Symmetrically and unsymmetrically substituted diarylcyclobutenes are synthesized in 20-70% yields from alkyne precursors via cobalt-catalyzed [2+2] cycloadditions. The reactions proceed under mild conditions and provide access to differently substituted diarylethene derivatives. All the diarylcyclobutene products undergo reversible photoisomerization upon irradiation with UV/Vis light. The ring-closed isomers show different thermal stabilities towards reisomerization with half-lives ranging from 9 to 300 hours.